Solid state starters/controllers have found widespread use for controlling application of power to an AC induction motor. The conventional starter/controller, referred to hereinafter as simply a controller, uses solid state switches for controlling application of AC line voltage to the motor. The switches may be thyristors such as silicon controlled rectifiers (SCRs) or triacs.
Conventional controllers include a housing enclosing the solid state switches and a control circuit for controlling operation of the solid state switches: For configuring controller operation the motor controller may include push button switches for setting parameter functions and ranges. Indicator lights, such as LEDs, may be used for status indication. While such a user interface may be adequate for configuring the motor controller and for monitoring, the user interface may not be considered user friendly to some end users. Particularly, selecting parameters to monitor may be time consuming and allows only a single parameter to be monitored.
One application for such a controller is as an elevator starter. The motor controller may be used to drive a pump for an hydraulic elevator. Each time movement of an elevator car is commanded, then the motor controller must start the elevator motor until it reaches operating speed and then operate in a run mode. Such a motor controller may only be used for the up direction as gravity may be used for the down direction. One type of elevator starter, referred to as a soft starter, changes the on time of the solid state switches to control voltage and to ramp up motor current with a fixed connection.
Occasionally, an elevator system may experience some problem with the power system, causing downtime for the elevator. The elevator service technician may go to the site but not see any problem at that specific time. To try to solve the problem, the technician may need to buy or rent expensive monitoring equipment to record power system values to analyze the problem.
The present invention is directed to improvements in monitoring and diagnosis of an electrical system.